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Track Tests Prove Great Results
We first wrote about this 565-cubic-inch Dart “Big M” engine, equipped with Dart Big Chief II Pro Stock-type aluminum heads, back in our October ’04 issue. The engine builder was Quarter Mile Performance in Chatsworth, California, and at the time, we called it “possibly the world’s most powerful four-barrel big-block.” It produced 1037 horsepower at 7200 rpm and 806 lb-ft of torque at 5500 rpm–plenty stout by anyone’s standards.
This engine, and others like it, has opened up a brand-new chapter in the ever-evolving, wild world of Chevrolet power. By design it has a bore and stroke of 4.60 inches by 4.25 inches and Big Chief II heads, which are about 2 inches taller, that feature oval-shaped intake ports. This, they say, is for maximum cylinder filling. Years ago, creative racers would angle-mill heads to arrive at the desired combustion chamber size and to improve the valve angle in combination with the incoming intake flow. These heads are nicknamed “11-degree” heads, as they have been designed with a built-in 11-degree angle right out of the box. There’s no angle milling needed here. A special valvetrain is necessary, along with longer stem valves. Quarter Mile Performance feels that these heads are worth 200 additional horsepower over the very best “shorter” heads.
The short-block features a Crower Ultra-Light crankshaft with Bill Miller connecting rods and pistons. The camshaft is a Comp Cams roller with a split valve lift of 0.850-inch intake and 0.775-inch exhaust. The duration is also split at 282/292 degrees. The original four-barrel intake manifold is a Dart item designed for this application. The carburetor is a DaVinci-prepped Holley 1150cfm Dominator. But there’s more.
Thinking we had seen something truly memorable at Quarter Mile Performance’s shop six months earlier, we were not prepared for a recent telephone call from Brad Lagman and Mike Consolo to let us know that the engine was now updated with a Ray Franks tunnel-ram intake manifold and a second identical DaVinci-prepped 1150cfm Holley Dominator carburetor. The owner of the engine wanted to compete in the new 6.20-8.00 e.t. bracket and hoped to be in the middle of the elapsed-time field in a 2200-pound rear engine dragster. Much-needed torque, resulting in additional horsepower, should enable him to do that. The combination seemed to love the additional induction and carburetion, as the Ray Franks tunnel ram and second carburetor netted 1175 horsepower, an addition of 138 horses, with a torque output of 860 lb-ft at 7200 rpm, a gain of some 63 to 100 lb-ft across the band.
In the real world, on the dragster’s initial runs with the tunnel ram, the 4000-rpm-stall-speed torque converter was no match. A higher stall speed was needed, as were traction adjustments. As it was, the dragster ran consistent 7.20 elapsed times at 185 mph. With high-6-second potential clearly within reach, the tunnel-ram-equipped Quarter Mile Performance/Dart 565 certainly sports a swagger befitting such a healthy big-block. We’ll let you know how it all progresses.
